1. Field of the Invention
The present invention relates generally to the field of protective devices and systems for electrical power transmission and distribution systems, and more particularly to a protective device and system including a pole-unit protective device that provides tripping of interrupters on multiple poles from a line-potential tripping device of each of the pole-unit protective devices.
2. Description of the Related Art
Power transformers and other electrical equipment in the electrical power transmission and distribution field are connected to a power source through various switching and protection devices so as to provide the required desirable protection to the power transformers and electrical devices as well as desirable versatility and flexibility in supplying various load circuits in the electrical power system. For example various fuses, circuit-switchers and circuit breakers are known to provide this protection.
While the prior art arrangements may be useful to provide protective devices with various features, these prior arrangements do not provide desirable protection without extensive demands on space, cost and external controls and associated wiring.
Accordingly, it is a principal object of the present invention to provide a multi-pole protective device and system for electrical power transmission and distribution systems that operates a multi-pole tripping system at ground level from a line-potential tripping device contained within each pole of the multi-pole system.
It is another object of the present invention to provide a protective arrangement including multiple pole-unit assemblies each of which is responsive to sensed overcurrents to provide a tripping signal to operate the multiple-pole unit assemblies.
It is a further object of the present invention to provide a protective device that is totally self-contained and that generates a tripping signal in response to overcurrent conditions to operate a ground-potential operating mechanism.
It is yet another object of the present invention to provide a protective device arrangement including multiple pole units that each include an internal line-potential tripping arrangement that communicates a trip signal to a ground-potential operating mechanism of the pole unit and associated pole units of the protective device arrangement.
It is a still further object of the present invention to provide a self-contained protective device pole-unit assembly that includes an interrupter, a ground-potential operating mechanism, and a line-potential trip arrangement for sensing overcurrents and operating the ground-potential operating mechanism to open the interrupter.
These and other objects of the present invention are efficiently achieved by the provision of a multi-pole protective device and system for electrical power transmission and distribution systems that operates a multi-pole tripping system at ground level from a line-potential tripping device contained within each pole of the multi-pole system. The system includes multiple pole-unit assemblies each of which is responsive to sensed overcurrents to provide a tripping signal. Each of the pole-unit assemblies is totally self-contained and generates a tripping signal in response to overcurrent conditions to operate a ground-potential operating mechanism. In one arrangement, the pole units each include an internal line-potential tripping arrangement that communicates a trip signal to a ground-potential operating mechanism of the pole unit and associated pole units of the protective device arrangement. Each pole unit also includes an interrupter operated by the ground-potential operating mechanism to open the interrupter. In such an arrangement, the pole units are mechanically independent of each other providing flexibility of location and ease of installation. Thus, the only interconnections between the pole units is the communication of the trip signal via electrical lines or the like. In a preferred arrangement, the line-potential tripping arrangement includes an insulated member that is moved to transmit the trip signal from line potential to ground potential. Also in a preferred arrangement, the movement of the insulated member generates a trip signal to operate the operating mechanism of the pole unit and associated pole units. In an alternate arrangement, the movement of the insulated member controls an electrical circuit to provide tripping signals to the pole units. In a particular arrangement, the operating mechanism of each pole unit is individually recharged manually via a tool affixed to a hot stick or the like. The recharging of the operating mechanism of each pole unit functions to close the interrupter thereof In a particular arrangement, the line-potential tripping arrangement of the pole unit is also reset during the recharging so as to be ready for tripping and operating the pole unit.